Manly-Looking Men May Have Poorer Semen Quality

WHY YOU SHOULD CARE

Because the biggest, strongest dude in the bunch might not necessarily be the most fertile.

September 16, 2014

Quality doesn’t always come in strong, sturdy packages — at least when it comes to sperm.

A recent study in the Journal of Evolutionary Biology bolstered earlier findings that hotter dudes have higher-quality sperm; that the little guys moved faster, and more of them looked physically normal, making it more likely that they would fertilize an egg. But here’s a twist:

Studies have shown that women tend to prefer men with attractive faces — symmetrical faces with clear skin, for example — since they might signal health and intelligence, characteristics that they can pass on to their children. But few studies have investigated whether men’s facial attractiveness could also indicate their fertility.

To find out, scientists from the University of Valencia in Spain, the University of Western Australia and other institutions asked college dudes to get down and dirty, analyzing ejaculated semen from 50 white University of Valencia students. They peered at the samples through a microscope to calculate the percentage of motile and normal-looking sperm in each, and took frontal and profile photos of each volunteer.

Manly-looking men tend to have more sex, so even if their sperm isn’t top-notch, they still stand a good chance of impregnating their mates.

They also recruited about 200 students from the University of Valencia and the Universidad del Norte in Colombia — all heterosexual — to evaluate the photos. They asked the female students from each group to rank the men’s attractiveness as possible long-term partners, and the men to rate how attractive the sperm donors might appear to a straight woman.

The scientists then rated the masculinity of each donor’s face, measuring characteristics that earlier studies had found differ strikingly in men versus women — like cheekbone width, which is larger in men and has been shown to correlate with testosterone levels and testosterone-linked traits, like aggressiveness and physical strength.

Sure enough, men rated as more attractive, generally, tended to have healthier semen. But cheekbone width was negatively associated with sperm quality. In other words, “men with more masculine (i.e., wider) faces tend to have poorer-quality semen than more feminine-faced men,” the study authors wrote.

Why? Maybe because the heightened testosterone levels that contribute to masculine features can impair sperm production. Or there may be a trade-off between how much sex men have and their sperm quality. The study notes that some researchers theorize that manly-looking men tend to have more sex, so even if their sperm isn’t top-notch, they still stand a good chance of impregnating their mates and passing on their genes. But less masculine guys — even if they’re generally nice to look at — hit it less and need to capitalize on every coital encounter.

Of course, the researchers note that they need to conduct further studies to determine whether their findings apply to other cultural groups, too. But they still suggest that brute and brawn don’t always win the race.